Robust catheter tubing

Abstract

A balloon catheter having a multilayer catheter shaft is formed to have an inner layer and an outer layer, where the inner layer and outer layer are selected from materials that enhance the pushability of the catheter while preserving the flexibility. Using a combination of a high Shore D duromater value material and a lower Shore D duromater value material, various combinations of multilayer catheter shafts are disclosed utilizing different glass transition temperatures and block copolyamides to obtain the desired characteristics.

We claim: 
     
       1. A method of forming an elongated, flexible catheter, comprising:
 forming a shaft having a proximal end, a distal end, and a lumen extending therein, the shaft having an inner layer comprising an amorphous polyamide having a Shore D durometer value of greater than 78, and an outer layer comprising a semi-crystalline polyamide or copolyamide having a Shore D durometer value of less than 76, wherein the outer layer is thinner than the inner layer, the shaft having an increased resistance to kinking as compared to a similar shaft of a single layer of the amorphous polyamide having a Shore D durometer value of greater than 78; and 
 providing a working device disposed on the distal end of the shaft. 
 
     
     
       2. The method of  claim 1 , wherein the working device is an inflatable balloon. 
     
     
       3. The method of  claim 1 , wherein the amorphous polyamide of the inner layer has a glass transition temperature of greater than 100° C. 
     
     
       4. The method of  claim 1 , wherein the polyamide or copolyamide of the outer layer has a glass transition temperature of less than 55° C. 
     
     
       5. The method of  claim 1 , wherein the amorphous polyamide of the inner layer and the polyamide or copolyamide of the outer layer have a common amide block. 
     
     
       6. The method of  claim 5 , wherein the common amide block is selected from the group consisting of nylon 12, nylon 11, nylon 6, and nylon 6,6. 
     
     
       7. The method of  claim 1 , wherein the inner polyamide includes at least one segment selected from the group consisting of cycloaliphatic segments, aliphatic segments, and aromatic segments. 
     
     
       8. The method of  claim 1 , wherein the inner polyamide comprises at least two segments selected from the group consisting of aliphatic segments, aromatic segments, and cycloaliphatic segments. 
     
     
       9. The method of  claim 1 , wherein the inner and outer layers are fowled by co-extrusion. 
     
     
       10. The method of  claim 9 , wherein the catheter shaft is tapered. 
     
     
       11. The method of  claim 9 , wherein the catheter shaft has a necked diameter portion. 
     
     
       12. The method of  claim 1 , wherein the outer layer is a polymer of nylon or a block copolymer of nylon. 
     
     
       13. The method of  claim 12 , wherein the nylon is nylon 11, nylon 12, nylon 6, nylon 6,6 or nylon 6,12. 
     
     
       14. The method of  claim 12 , wherein the block copolymer is a block copolymer of nylon and polytetramethylene oxide. 
     
     
       15. The method of  claim 14 , wherein the nylon is nylon 11, nylon 12, nylon 6, nylon 6,6 or nylon 6,12. 
     
     
       16. The method of  claim 1 , wherein the outer layer comprises a block copolymer of nylon 12 and polytetramethylene oxide. 
     
     
       17. The method of  claim 1 , wherein the shaft has an enhanced resistance to solvents as compared to a similar shaft of a single layer of the amorphous polyamide having a Shore D durometer value of greater than 78. 
     
     
       18. The method of  claim 1 , wherein the outer layer is thinner than the inner layer along substantially an entire length of the shaft extending from the proximal end to the distal end. 
     
     
       19. A method of forming an elongated, flexible catheter, comprising:
 forming a shaft having a proximal end, a distal end, and a lumen extending therein, the shaft having an inner layer comprising high density polyethylene and an outer comprising a blend of two polymers, including a first polymer being an amorphous nylon having a Shore D durometer value of greater than 78 and a second polymer having a Shore D durometer value of no more than 76, wherein the inner layer is thicker than the outer layer, the shaft having an increased resistance to kinking as compared to a similar shaft having an inner layer of the high density polyethylene and an outer layer of the amorphous nylon having a Shore D durometer value of greater than 78; and 
 providing a working device disposed on the distal end of the shaft. 
 
     
     
       20. The method of  claim 19 , further comprising forming an intermediate layer disposed between the inner layer and the outer layer, the intermediate layer serving as a bonding layer. 
     
     
       21. The method of  claim 19 , wherein the first polymer and the second polymer have a common amide block. 
     
     
       22. The method of  claim 21 , wherein the common amide block is selected from the group consisting of nylon 12, nylon 11, nylon 6, and nylon 6,6. 
     
     
       23. The method of  claim 19 , wherein the first polymer includes at least one segment selected from the group consisting of cycloaliphatic segments, aliphatic segments, and aromatic segments. 
     
     
       24. The method of  claim 19 , wherein the first polymer comprises at least two segments selected from the group consisting of aliphatic segments, aromatic segments, and cycloaliphatic segments. 
     
     
       25. The method of  claim 19 , wherein the inner layer and outer layer are formed by co-extrusion. 
     
     
       26. The method of  claim 19 , wherein the second polymer is a semi-crystalline polymer of nylon or a block copolymer of nylon. 
     
     
       27. The method of  claim 26  wherein the nylon is nylon 11, nylon 12, nylon 6, nylon 6,6 or nylon 6,12. 
     
     
       28. The method of  claim 19 , wherein the block copolymer is a block copolymer of nylon and polytetramethylene oxide. 
     
     
       29. The method of  claim 19 , wherein the shaft has an enhanced resistance to solvents as compared to a similar shaft having an inner layer of the high density polyethylene and an outer layer of the amorphous nylon having a Shore D durometer value of greater than 78. 
     
     
       30. The method of  claim 19 , wherein the outer layer is thinner than the inner layer along substantially an entire length of the shaft extending from the proximal end to the distal end.